A negative syphilis toluidine red test is a serologic test for a non-syphilis spirochete antigen. Because the antigen used is not the syphilis spirochete itself, a negative test is not particularly meaningful for ruling out syphilis infection. Therefore, if you want to exclude syphilis infection, you should use the antigen of the syphilis spirochete for serological testing. A positive TPPA test means that the person has previously been infected with syphilis spirochetes. A negative toluidine red test, however, indicates that the person probably does not need any treatment at this time or that the syphilis patient has recovered from previous effective treatment. The toluidine red test, however, requires 1-3 years of follow-up before the results can be determined.